Abstract: In some examples, a system is configured to mount on a first vehicle. The system include an antenna configured to transmit a first surveillance message by forming an omni-directional beam. The antenna is also configured to receive a second surveillance message from a second vehicle during a first time period. The antenna is further configured to receive a third surveillance message from a third vehicle during a second time period, where the first and second time periods at least partially overlap in time. The system also includes processing circuitry configured to demodulate the second surveillance message by forming a first beam and demodulate the third surveillance message by forming a second beam. The second beam is different than the first beam, and the first beam is simultaneous with the second beam.

Abstract: In some examples, a system includes a transceiver configured to transmit a first surveillance message at a first power level at or below a first maximum power level. The system also includes processing circuitry coupled to the transceiver, the processing circuitry configured to determine that a threshold condition exists. The processing circuitry is also configured to determine a second maximum power level in response to determining that the threshold condition exists, where the second maximum power level is lower than the first maximum power level. The transceiver is configured to transmit, in response to the processing circuitry determining that the threshold condition exists, a second surveillance message at a second power level, wherein the second power level is at or below the second maximum power level.

Abstract: In some examples, a system includes a transceiver configured to transmit a first surveillance message at a first power level at or below a first maximum power level. The system also includes processing circuitry coupled to the transceiver, the processing circuitry configured to determine that a threshold condition exists. The processing circuitry is also configured to determine a second maximum power level in response to determining that the threshold condition exists, where the second maximum power level is lower than the first maximum power level. The transceiver is configured to transmit, in response to the processing circuitry determining that the threshold condition exists, a second surveillance message at a second power level, wherein the second power level is at or below the second maximum power level.

Abstract: In some examples, a system is configured to mount on a first vehicle. The system include an antenna configured to transmit a first surveillance message by forming an omni-directional beam. The antenna is also configured to receive a second surveillance message from a second vehicle during a first time period. The antenna is further configured to receive a third surveillance message from a third vehicle during a second time period, where the first and second time periods at least partially overlap in time. The system also includes processing circuitry configured to demodulate the second surveillance message by forming a first beam and demodulate the third surveillance message by forming a second beam. The second beam is different than the first beam, and the first beam is simultaneous with the second beam.

Abstract: Described herein is a calibration circuit for a multiple element antenna with two or more antenna transmit and receive elements. In some examples the multi-element antenna may also include a beamforming network that combine the multiple antenna radiating element inputs and outputs with controlled phase and amplitude relationships such that spatial beams can be formed by varying the phase and amplitudes of two or more signals applied to antenna input ports for the antenna. The calibration circuit of this disclosure may be used to obtain data to determine phase and amplitude offsets induced by the combined transmission elements, and any phase and amplitude offsets induced by the transmitter or receiver circuitry. The determined phase and amplitude offsets may then be removed from received signal measurements and compensated for in transmit signal generation.

Abstract: A traffic collision avoidance system (TCAS), configured to transmit a wide transmit beam of approximately 180 degrees. The wide transmit beam may be, for example at the interrogation frequency or a transponder response frequency. The TCAS of this disclosure includes a directional antenna system with two signal input ports and two or more antenna elements. In some examples, the direction of the 180 degree beam may be controlled by the phase relationship between the signals input to the two port antenna. In other examples, the direction of the transmit beam from the antenna system is predefined to be in two complementary directions (e.g., forward and aft).

Abstract: A traffic collision avoidance system (TCAS), configured to transmit a wide transmit beam of approximately 180 degrees. The wide transmit beam may be, for example at the interrogation frequency or a transponder response frequency. The TCAS of this disclosure includes a directional antenna system with two signal input ports and two or more antenna elements. In some examples, the direction of the 180 degree beam may be controlled by the phase relationship between the signals input to the two port antenna. In other examples, the direction of the transmit beam from the antenna system is predefined to be in two complementary directions (e.g., forward and aft).

Abstract: Described herein is a calibration circuit for a multiple element antenna with two or more antenna transmit and receive elements. In some examples the multi-element antenna may also include a beamforming network that combine the multiple antenna radiating element inputs and outputs with controlled phase and amplitude relationships such that spatial beams can be formed by varying the phase and amplitudes of two or more signals applied to antenna input ports for the antenna. The calibration circuit of this disclosure may be used to obtain data to determine phase and amplitude offsets induced by the combined transmission elements, and any phase and amplitude offsets induced by the transmitter or receiver circuitry. The determined phase and amplitude offsets may then be removed from received signal measurements and compensated for in transmit signal generation.

Abstract: In some examples, a system includes a transceiver configured to transmit a first surveillance message at a first power level at or below a first maximum power level. The system also includes processing circuitry coupled to the transceiver, the processing circuitry configured to determine that a threshold condition exists. The processing circuitry is also configured to determine a second maximum power level in response to determining that the threshold condition exists, where the second maximum power level is lower than the first maximum power level. The transceiver is configured to transmit, in response to the processing circuitry determining that the threshold condition exists, a second surveillance message at a second power level, wherein the second power level is at or below the second maximum power level.

Abstract: A system and techniques for automatically generating messages to advise air traffic control (ATC) when an aircraft should maneuver based on information from the aircraft guidance system. The techniques of this disclosure integrate guidance processing algorithms, such as those found in detect and avoid (DAA) systems, with data link communications, such as those in controller pilot data link communications (CPDLC), to communicate deviations from an approved flight plan to ATC. As one example, if an aircraft collision avoidance system determines that an aircraft should deviate from the aircraft's current flight path to avoid a hazard, the techniques of this disclosure include automatically generating a message, then sending the message to ATC. In some examples, the pilot may approve the message before allowing the system to send the message to ATC. The pilot may be on board a manned aircraft or a remote pilot of an unmanned aircraft system (UAS).

Abstract: A system for tracking a vehicle includes a transceiver configured to receive a first signal including first surveillance data from the vehicle at a first time, and receive a second signal from the vehicle at a second time. The system further includes processing circuitry configured to determine a first location and a first course of the vehicle at the first time based on the first surveillance data, and determine a change in power level from the first signal to the second signal. The processing circuitry is further configured to predict a maneuver for the vehicle based on the first location, the first course, and the change in power level from the first signal to the second signal.

Abstract: In one example, a method for generating air traffic alerts includes determining a predicted trajectory for a target air-craft, based at least in part on a comparison of information received on a recent trajectory of the target aircraft with a set of procedural trajectory information. The method further includes determining whether a violation of protected airspace is predicted between the target aircraft and an ownship, based at least in part on the predicted trajectory for the target aircraft and a predicted trajectory for the ownship. The method further includes generating an alert output in response to determining that the violation of protected airspace is predicted.

Abstract: A system for tracking a vehicle includes a transceiver configured to receive a first signal including first surveillance data from the vehicle at a first time, and receive a second signal from the vehicle at a second time. The system further includes processing circuitry configured to determine a first location and a first course of the vehicle at the first time based on the first surveillance data, and determine a change in power level from the first signal to the second signal. The processing circuitry is further configured to predict a maneuver for the vehicle based on the first location, the first course, and the change in power level from the first signal to the second signal.

Abstract: A system is described that is configured to receive surveillance data from a vehicle, determine a location of the vehicle based at least in part on the received surveillance data, and determine a course of the vehicle based at least in part on the received surveillance data. The system is further configured to predict a future vehicle maneuver for the vehicle based at least in part on the location and the course of the vehicle, and based at least in part on a set of protocol data indicating one or more standard procedures for one or more vehicle maneuvers. The system is further configured to determine, based at least in part on the predicted future vehicle maneuver, a modified protection volume for the vehicle that is modified relative to a baseline protection volume for the vehicle. The system is further configured to generate an output based on the modified protection volume.

Abstract: A system is described that is configured to receive surveillance data from a vehicle, determine a location of the vehicle based at least in part on the received surveillance data, and determine a course of the vehicle based at least in part on the received surveillance data. The system is further configured to predict a future vehicle maneuver for the vehicle based at least in part on the location and the course of the vehicle, and based at least in part on a set of protocol data indicating one or more standard procedures for one or more vehicle maneuvers. The system is further configured to determine, based at least in part on the predicted future vehicle maneuver, a modified protection volume for the vehicle that is modified relative to a baseline protection volume for the vehicle. The system is further configured to generate an output based on the modified protection volume.

Abstract: In one example, a method for generating air traffic alerts includes determining a predicted trajectory for a target air-craft, based at least in part on a comparison of information received on a recent trajectory of the target aircraft with a set of procedural trajectory information. The method further includes determining whether a violation of protected airspace is predicted between the target aircraft and an ownship, based at least in part on the predicted trajectory for the target aircraft and a predicted trajectory for the ownship. The method further includes generating an alert output in response to determining that the violation of protected airspace is predicted.

Abstract: This disclosure is directed to systems and methods for generating outputs based on collected aircraft maneuver data. In one example, a system is configured to collect surveillance data from one or more aircraft. The system is further configured to identify, from the collected surveillance data, aircraft maneuver data indicative of maneuvers of the one or more aircraft. The system is further configured to store the aircraft maneuver data in a data store. The system is further configured to perform one or more analyses of the stored aircraft maneuver data in the data store. The system is further configured to generate an output based on the one or more analyses of the stored aircraft maneuver data.

Abstract: This disclosure is directed to systems and methods for generating outputs based on collected aircraft maneuver data. In one example, a system is configured to collect surveillance data from one or more aircraft. The system is further configured to identify, from the collected surveillance data, aircraft maneuver data indicative of maneuvers of the one or more aircraft. The system is further configured to store the aircraft maneuver data in a data store. The system is further configured to perform one or more analyses of the stored aircraft maneuver data in the data store. The system is further configured to generate an output based on the one or more analyses of the stored aircraft maneuver data.

Abstract: This disclosure is directed to systems and methods for aircraft collision avoidance with speed-based collision alert time thresholds. In one example, a system is configured to determine predicted trajectories for an own aircraft and a target aircraft. The system is further configured to determine whether a violation of protected airspace is predicted between the own aircraft and the target aircraft. The system is further configured to determine whether a predicted time to closest approach between the own aircraft and the target aircraft is less than an alert threshold time based on a speed of the own aircraft. The system is further configured to generate an alert output, in response to determining that a violation of protected airspace is predicted and that the predicted time to closest approach between the own aircraft and the target aircraft is less than the alert threshold time based on the speed of the own aircraft.

Abstract: This disclosure is directed to systems and methods for aircraft collision avoidance with speed-based collision alert time thresholds. In one example, a system is configured to determine predicted trajectories for an own aircraft and a target aircraft. The system is further configured to determine whether a violation of protected airspace is predicted between the own aircraft and the target aircraft. The system is further configured to determine whether a predicted time to closest approach between the own aircraft and the target aircraft is less than an alert threshold time based on a speed of the own aircraft. The system is further configured to generate an alert output, in response to determining that a violation of protected airspace is predicted and that the predicted time to closest approach between the own aircraft and the target aircraft is less than the alert threshold time based on the speed of the own aircraft.